lecture 11, part 1: coded imaging - mit opencourseware · mitsubishi electric research labs (merl)...

Camera CultureCamera Culture

Ramesh RaskarRamesh Raskar

MIT Media LabMIT Media Lab

http://cameraculture.media.mit.edu/

Computational Camera & Photography: Coded Imaging

Computational Camera & Computational Camera & Photography: Coded ImagingPhotography: Coded Imaging

http://cameraculture.media.mit.edu/

Image removed due to copyright restrictions.See Fig. 1, “Eight major types of optics in animal eyes.”In Fernald, R. D. “Casting a Genetic Light on the Evolution of Eyes.”Science 313, no. 5795 (September 29, 2006): 1914-1918.http://dx.doi.org/10.1126/science.1127889

http://dx.doi.org/10.1126/science.1127889

Traditional Camera

Shutter is OPEN

Blurring

==

Convolution

Traditional Camera: Box Filter

Sinc Function

f

|H(f)|

Source: Raskar, Agrawal and Tumblin. “Coded Exposure Photography: Motion Deblurring via Fluttered Shutter.”Proceedings of SIGGRAPH 2006.

Blurring Process for Linear Motion

*

T

=

T


Deblurring Process

A \ bSmearMatrix

BlurredImage

\

T

UnknownImage=?

- Condition number for the smearing matrix is large- Thus invertibility is bad


Input ImageSource: Raskar, Agrawal and Tumblin. “Coded Exposure Photography: Motion Deblurring via Fluttered Shutter.”Proceedings of SIGGRAPH 2006.

Rectified Crop

Deblurred Result

Source: Raskar, Agrawal and Tumblin. “Coded ExposurePhotography: Motion Deblurring via Fluttered Shutter.”Proceedings of SIGGRAPH 2006.

Deblurred ResultInput Photo


Traditional Camera

Shutter is OPEN

Our Camera

Flutter Shutter

Shutter is OPEN and CLOSED

Comparison of Blurred Images

Implementation

Completely Portable

Mitsubishi Electric Research Labs (MERL) Coding and Modulation in Cameras

Flutter Shutter On PointGrey CameraFlutter Shutter On PointGrey Camera

• Dragonfly2 camera

• External Trigger – Mode 5– Multiple Exposure Pulse Width Mode

• On Chip Fluttered Integration, no extra cost

Courtesy of MERL. Used with permission.

Lab Setup

Blurring

==

Convolution

Traditional Camera: Box Filter

Sinc Function

f

|H(f)|


Flutter Shutter: Coded Filter

Preserves High Spatial Frequencies

f

|H(f)|


Comparison

f

|H(f)|

f

|H(f)|


Inverse Filter Unstablef

|1/H(f)|


Inverse Filter stable

f

|1/H(f)|

Short Exposure Long Exposure

Matlab Lucy


Coded Exposure

Our result

Ground Truth

Motion Blur as Convolution


?

??

Convolution == Linear System

Solving

Are all codes “good”?

Alternate

All ones

Random

Our Code

f

f

f

f

|H(f)|

|H(f)|

|H(f)|

Need to consider zero padded codes

f

f

f

|H(f)|

|H(f)|

|H(f)|

License Plate Retrieval


Camera Limitations and TradeoffsCamera Limitations and Tradeoffs

• Low dynamic range

• Resolution vs Noise

• Motion blur– Reduce shutter speed, but lose light

• Limited depth of field– Reduce aperture, but lose light– Increase shutter time, but motion blur

Courtesy of MERL. Used with permission.


Changing Aperture SizeChanging Aperture Size

• Samuel Hasinoff and Kiriakos Kutulakos, ‘A Layer-Based Restoration Framework for Variable-Aperture Photography’ ICCV 2007

Images removed due to copyright restrictions.

Mitsubishi Electric Research Labs (MERL) Coding and Modulation in CamerasHow to handle How to handle focus blur?focus blur?

Source: Veeraraghavan, Raskar, Agarwal, Mohan, and Tumblin. “Dappled Photography: Mask Enhanced Cameras for Heterodyned Light Fields and Coded Aperture Refocusing.” Proceedings of SIGGRAPH 2007.

Mitsubishi Electric Research Labs (MERL) Coding and Modulation in CamerasCodedCoded ExposureExposure (Flutter Shutter)(Flutter Shutter)

Raskar, Agrawal, TumblinRaskar, Agrawal, TumblinSIGGRAPH 2006SIGGRAPH 2006

CodedCoded ApertureAperturewith Veeraraghavan, Raskar, Tumblin, & Mohanwith Veeraraghavan, Raskar, Tumblin, & Mohan,,

SIGGRAPH 2007SIGGRAPH 2007

Temporal 1Temporal 1--D broadband code: D broadband code: MotionMotion DeblurringDeblurring

Spatial 2Spatial 2--D broadband code:D broadband code:FocusFocus DeblurringDeblurring


In Focus Photo

LED


Out of Focus Photo: Open Aperture


Out of Focus Photo: Coded Aperture

Blurred Photos

Coded Aperture, 7 * 7 MaskOpen ApertureSource: Veeraraghavan, Raskar, Agarwal, Mohan, and Tumblin. “Dappled Photography: Mask Enhanced Cameras for Heterodyned Light Fields and Coded Aperture Refocusing.” Proceedings of SIGGRAPH 2007.

Deblurred Photos

Coded Aperture, 7 * 7 MaskOpen ApertureSource: Veeraraghavan, Raskar, Agarwal, Mohan, and Tumblin. “Dappled Photography: Mask Enhanced Cameras for Heterodyned Light Fields and Coded Aperture Refocusing.” Proceedings of SIGGRAPH 2007.

Mitsubishi Electric Research Labs (MERL) Coding and Modulation in CamerasCaptured Blurred Captured Blurred

PhotoPhoto



Refocused on Person


MERL,Northwestern Univ.

Mask-Enhanced Cameras: Heterodyned Light Fields & Coded Aperture Veeraraghavan, Raskar, Agrawal, Mohan & Tumblin

Blur Estimation & SegmentationBlur Estimation & Segmentation

Captured Blurred Photo

Deblur at different blur

sizes k

k = 10

k = 1

•Defocus blur dependent on depth

•Assumptions

•Layered Lambertian Scene

•Constant blur within each layer



k = 10

k = 1

DeblurredImages

Define Cost FunctionDefine Cost Function

Cost Function Images

Likelihood Error: (Blurred image - Sharp Image * PSFk)2

Gradient Error: Natural Image Statistics, Gradient Kurtosis

k = 1

k = 10



Blur Estimation & Segmentation == LabelingBlur Estimation & Segmentation == Labeling

• Graph cuts for labeling

Error Images

K = 7

K = 1k = 10

k = 1

CapturedPhoto

Deblur, k = 7

Reblur

Fusion




Weighted Deconvolution



Blocking Light == More InformationBlocking Light == More Information

Coded ExposureCoded ExposureCoding in Time Coding in Time

Coded ApertureCoded ApertureCoding in SpaceCoding in Space

Mask? Sensor

MaskSensorMask? Sensor

MaskSensor

Mask? Sensor

4D Light Field from 2D Photo:

Heterodyne Light Field Camera

Full Resolution Digital Refocusing:

Coded Aperture Camera

Conventional Lens: Limited Depth of FieldConventional Lens: Limited Depth of Field

SmallerAperture

OpenAperture

Slide by Shree NayarCourtesy of Shree Nayar. Used with permission.

Wavefront Coding using Cubic Phase PlateWavefront Coding using Cubic Phase Plate

"Wavefront Coding: jointly optimized optical and digital imaging systems“,E. Dowski, R. H. Cormack and S. D. Sarama , Aerosense Conference, April 25, 2000


Depth Invariant BlurDepth Invariant Blur

Conventional System Wavefront Coded System


Typical PSF changes slowly Designed PSF changes fast

Decoding depth via defocus blur

• Design PSF that changes quickly through focus so that defocus can be easily estimated• Implementation using phase diffractive mask

(Sig 2008, Levin et al used amplitude mask)

Phase mask

R. Piestun, Y. Schechner, J. Shamir, “Propagation-Invariant Wave Fields with Finite Energy,” JOSA A 17, 294-303 (2000)R. Piestun, J. Shamir, “Generalized propagation invariant wave-fields,” JOSA A 15, 3039 (1998)



Image removed due to copyright restrictions.

Rotational PSFRotational PSF

R. Piestun, Y. Schechner, J. Shamir, “Propagation-Invariant Wave Fields with Finite Energy,” JOSA A 17, 294-303 (2000)R. Piestun, J. Shamir, “Generalized propagation invariant wave-fields,” JOSA A 15, 3039 (1998)

Images removed due to copyright restrictions.Two sequences showing rotating and standard PSF.

Single Pixel Camera

Slides by Shree Nayar

Several slides removed due to copyright restrictions.

MIT OpenCourseWarehttp://ocw.mit.edu

MAS.531 / MAS.131 Computational Camera and PhotographyFall 2009

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lecture 11, part 1: coded imaging - mit opencourseware · mitsubishi electric research labs (merl)...

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